In the automobile sector, headlamps which simultaneously fulfill a plurality of lighting technology functions or light functions (low beam, high beam, cornering light, etc.) are known. In order to generate the light of the light functions, a plurality of light sources are used, which are activated individually or in predetermined groups depending on the light function. In this case, some of the light functions may be produced by one of the other light functions plus dedicated light generation (for example high beam from low beam and an additional wide-emitting light beam, cornering light from daytime running light and an additional laterally oriented light beam, etc.). A disadvantage in this case is that a relatively large number of light sources are required.
In bi-xenon or bi-halogen projection systems for motor vehicles, only a single gas discharge light source is used, in order, with a reflector cavity, a shutter and a projection lens, to switch the low beam function and the high beam function alternately in a motor vehicle headlamp.
Particularly in the case of light functions which have similar requirements in terms of their light distribution pattern but differ in their integral luminous flux, brightness adaptation (dimming) of one light source may be used in conjunction with the same optical unit in order to be able to switch the two light functions alternately. An example of this is the H15 incandescent lamp, which has two filaments, one of which is used only as a light source for daytime running light and position light and both together generate the low beam light.